Heretofore, various metal oxides including iron, nickel, and cobalt oxides have been employed to remove arsenic from hydrocarbon charge stocks, such as naphtha or straight run gasoline, all obtained from naturally occurring crude oil. By employing the oxides at Low temperature such as from room temperature to 250.degree. F, by disregarding the atmosphere under which the reaction takes place, and by using substantial amounts of water, the oxide acts as an oxidizing agent and oxidizes the arsenic to a water soluble arsenic oxide. In this way the arsenic oxide is dissolved in the water and removed from the hydrocarbonaceous liquid. This process is fully and completely disclosed in U.S. Pat. No. 2,778,779, the disclosure of which is incorporated herein by reference.
Also, heretofore, arsenic has been removed from similar naturally occurring hydrocarbonaceous liquids including crude oil by contacting the hydrocarbonaceous liquid with a metal salt of a strong acid at low temperatures such as room temperature and without regard to the atmosphere under which the contacting takes place. In this particular process it was taught that oxides do not work for removing arsenic. This process is fully and completely disclosed in U.S. Pat. No. 2,781,297, the disclosure of which is incorporated herein by reference.
Processes that work for removing other contaminants, or catalyst-poisoning materials, such as organo-metallic compounds like iron porphyrins, are frequently inoperable for removing impurities like arsenic. For example, the catalytic hydrogenation of hydrocarbons to effect precipitation of an insoluble iron salt of the iron porphyrins within a hydrogenating catalyst, as described in U.S. Pat. No. 3,496,099, cannot be employed satisfactorily in removing arsenic from synthetic crudes or the like.
In fact, none of the prior art processes have been completely satisfactory in removing catalyst-poisoning impurities, such as arsenic, from synthetic crude oil and synthetic oil fractions.